Project Summary Uveal melanoma (UM) is a highly aggressive eye cancer that leads to metastatic death in up to half of patients. UM has a propensity to undergo early micrometastasis prior to treatment of the primary tumor, with later emergence of overt metastatic disease. Consequently, there has been no measurable improvement in survival over the past half century. The overall objective of our research program is to improve survival by developing highly accurate prognostic tests, based on biomarkers we discovered in the lab. In this proposal, we propose to (1) stratify patients with high-risk medium and large UMs to adjuvant therapy and increased metastatic surveillance, and (2) stratify patients with high-risk small UMs to early preemptive treatment of the primary tumor. During previous funding periods, we developed a highly innovative UM gene expression profile-based prognostic test (UM-GEP) that has been commercialized and is now used by a majority of centers in the US and beyond, to asses metastatic risk and make management decisions. Despite being recognized as the first- in-class industry standard in the field, there is a critical need to further improve its prognostic accuracy. We have since discovered new prognostically significant mutations in BAP1 and SF3B1 and a new mRNA biomarker (PRAME) that will set a new standard for prognostic accuracy, while also guiding the choice of systemic therapy. In this competitive renewal, we propose (1) to perform a landmark prospective 28-center study to optimize and validate these new biomarkers to expand the prognostic ability of the UM-GEP test and guide the choice of systemic therapy, and (2) to develop a ground breaking new prognostic test based on circulating exosomal microRNA profiling performed on routine blood samples, which will greatly expand the number of patients with benign and malignant uveal melanocytic tumors who will directly benefit from this personalized genomic medicine approach.